Set up a youshop account with NZ Post (its free, you just pay for shipping)? You get both a US and UK shipping address you can use for stuff like this... There are restrictions on weight and size, however. But its a good option for buying anything that doesn't do international. Also, the general cost is around NZ$17 from youshop - if the eBay seller is doing free national shipping, and their international is crazy expensive - that's another reason its handy.
You can check it out here:http://www.nzpost.co.nz/tools/youshop